When a dynamic range of a scene exceeds a dynamic range of a camera sensor, a photographed image may be overexposed or underexposed and content of the scene cannot be truly restored. HDR (High Dynamic Range, high dynamic range) synthesis means that one highly dynamic image is obtained by synthesizing images with different exposure, and a dynamic range of the image that is obtained by means of synthesis can truly reflect content of a current scene. Therefore, before HDR synthesis is performed, multiple images with different exposure (generally two or three sheets) need to be photographed. Exposure needs to be determined according to a current scene, and desired exposure ensures that the images with different exposure may record details of a bright location and a dark location in the scene. In this way, the content of the current scene can be truly recorded only by using an HDR synthesis technology.
In the prior art, the images with different exposure that are required for the HDR synthesis are generally acquired in a manner of exposure bracketing. The so-called exposure bracketing is to increase or decrease exposure on the basis of normal exposure, to acquire the images with different exposure. The increased or decreased exposure is generally fixed, and there is a time interval between the images with different exposure.
The prior art has at least the following technical problem:
Because in the prior art, images with different exposure are acquired by increasing or decreasing fixed exposure on the basis of an image with normal exposure, there is a technical problem that a required group of desired exposure cannot be determined according to a current scene.